A257535 Decimal expansion of the imaginary part of -E_1(i), i being the imaginary unit.

6, 2, 4, 7, 1, 3, 2, 5, 6, 4, 2, 7, 7, 1, 3, 6, 0, 4, 2, 8, 9, 9, 6, 8, 3, 7, 7, 8, 1, 6, 5, 7, 1, 7, 8, 4, 2, 8, 6, 2, 4, 6, 7, 4, 4, 9, 4, 9, 4, 4, 1, 1, 2, 0, 0, 1, 6, 0, 1, 7, 5, 2, 2, 5, 8, 7, 2, 2, 1, 1, 6, 6, 6, 0, 2, 3, 0, 6, 5, 8, 1, 2, 2, 5, 3, 1, 5, 2, 7, 9, 5, 8, 9, 3, 1, 7, 8, 2, 2, 7, 7, 6, 0, 5, 0

Offset: 0

Author

Stanislav Sykora, Apr 28 2015

Keywords

• nonn
• cons

Comments

E_1(z) = Integral_{t>=1}(exp(-t*z)/t) is the exponential integral.

Examples

			0.6247132564277136042899683778165717842862467449494411200160175...
		

Links

• Stanislav Sykora, Table of n, a(n) for n = 0..2000
• Wikipedia, Exponential integral.

Crossrefs

Cf. A099281, A099282, A099285.

Programs

Mathematica

RealDigits[Pi/2 - SinIntegral[1], 10, 105][[1]] (* Amiram Eldar, May 24 2023 *)

PARI

a = imag(-eint1(I))

Formula

Equals imag(E_1(-i)).

Equals (Pi/2) - A099281.